I found a problem which was not present in the previous version. When I am mixing video from two webcams, video from the foreground camera can be expanded only in horizontal direction. Only the vertical dashed line shows and by moving it I can expand video in horizontal direction fully. The horizontal dashed line is not showing up at all and video can not be expanded in vertical direction as can be seen here:

In consequence, when fully expanded, the video from the foreground camera does not cover the display completely, there is a stripe from background camera visible as in this picture:

I am running Windows 10 64-bit Creators with two webcams @1920x1080 resolution. The webcams are of the type which have video encoder on-board but this should not be an issue since my system was working perfectly with the previous version.